This Clinical Laboratory Core will provide an efficient centralized laboratory for routine handling and analyses of clinical specimens in support of Projects 1 and 2. The specific functions of the Core Laboratory are: 1. To process blood and fluid samples collected in the clinical studies (Project 1) for utilization in Projects 1 and 2 and this Core, 2. To perform diagnostic serologic and virologic assays for Projects 1 and 2, 3. To quantify the levels of dengue virus RNA in plasma/serum samples by fluorogenic RT-PCR for Projects 1 and 2, and 4. To perform flow cytometry analyses on fresh blood samples for Projects 1 and 2. The Core Laboratory will be located in facilities of the Department of Virology, Armed Forces Research Institute of Medical Sciences in Bangkok and Kamphaeng Phet, Thailand. The Department has over 40 years of experience in flavivirology and clinical studies. A Core Clinical Laboratory will operate in Thailand to process the large number of clinical specimens collected in this research program and will perform routine laboratory tests for Projects 1 and 2. This organization provides an efficient system for routine procedures that support our research.